Comparative validity and reproducibility of questionnaires in assessing types, frequency, and quantity of sweetened beverage consumption among Mahidol University students

Background: Excessive consumption of sugar-sweetened beverages (SSB) is a modifiable risk factor of chronic non-communicable diseases. Accurate and context-specific assessment tools are needed to capture emerging beverage types and to estimate beverage-related sugar intake among university students. Objective: This study aimed to evaluate the reproducibility and relative validity of a modified Beverage Intake Questionnaire (ModBEVQ) for assessing beverage types, consumption frequency, volume, and total sugar intake of sweetened beverage consumption among Mahidol university students. Design: A validation study was conducted among 122 students at Mahidol University, Thailand. Reproducibility was assessed by comparing two administrations of the ModBEVQ conducted 1 month apart. Relative validity was assessed by comparing the second BEVQ with a 4-day beverage record (4dBR). Statistical analyses included Spearman’s rank correlation coefficient (r) and Intraclass Correlation Coefficients (ICC), and Bland–Altman analysis. Results: Reproducibility coefficients of the ModBEVQ ranged from 0.27 to 0.84 for beverage volume and from 0.20 to 0.82 for total sugar intake. Relative validity coefficients ranged from 0.16 to 0.65 for beverage volume and from 0.20 to 0.58 for total sugar intake, indicating variable performance across beverage outcome. Bland–Altman analysis demonstrated a small mean bias between the ModBEVQ and the 4dBR. The wide 95% limits of agreement indicated considerable disagreement between the methods at the individual level. Conclusion: The ModBEVQ demonstrates variable reproducibility and weak-to-moderate relative validity overall, with stronger performance for some beverage outcomes. It may be useful for estimating average beverage volume and sugar intake at the group-level and may have potential applications in epidemiological surveillance and public health monitoring in Thailand, particularly among university students and similar young-adult populations. However, it should not be used to estimate individual beverage intake.